PURPOSE: To reduce the power consumption, by providing the control terminal to the built-in constant voltage generating circuit and thus breaking the current of the circuit group which is not used.

CONSTITUTION: With connection of the control terminal CONT of a constant current generating circuit to the 2nd power source VEE, the potential at the point (a) is clamped at the potential which is higher than VEE by the forward voltage VF of the diode D. As a result, the transistor Q2 becomes nonconductive along with the transistor Q1. In this instant, the potential of the point (b) at the VEE level with the output of the constant current source dropped to zero. Thus only the current that passes through the resistance R3 and diode D is consumed.